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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var name = "window";
        var Tom = {
            name:"Tom",
            show:function(){
                console.log(this.name)
            },
            wait:function(){
                var fun = this.show;
                fun()
            }
        }
        Tom.wait() //'window'
    </script>
</body>

</html>